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The Himalayan orogenic system is one of the youngest and most spectacular examples of a continent-continent collision on earth. Although the collision zone has been the subject of extensive research, fundamental questions remain concerning the architecture and evolution of the orogen. Of particular interest are the structures surrounding the 5 km high Tibetan Plateau, as these features record both the collisional and post-collisional evolution of the orogen. In this study we examine structures along the southwestern margin of the Tibetan Plateau, including the Karakoram (KFS) and Longmu Co (LCF) faults, and the Ladakh, Pangong and Karakoram Ranges. New low-temperature thermochronology data collected from across the Ladakh, Pangong and Karakoram Ranges improved the spatial resolution of exhumation patterns adjacent to the edge of the plateau. These data show a southwest to northeast decrease in cooling ages, which is the trailing end of a wave of decreased exhumation related to changes in the overall amount of north-south shortening accommodated across the region. We also posit that north-south shortening is responsible for the orientation of the LCF in India. Previously, the southern end of the LCF was unmapped. We used ASTER remotely sensed images to create a comprehensive lithologic map of the region, which allowed us to map the LCF into India. This mapping shows that this fault has been rotated into parallelism with the Karakoram fault system as a result of N-S shortening and dextral shear on the KFS. Additionally, the orientation and sense of motion along these two systems implies that they are acting as a conjugate fault pair, allowing the eastward extrusion of the Tibet. Finally, we identify and quantify late Quaternary slip on the Tangtse strand of the KFS, which was previously believed to be inactive. Our study found that this fault strand accommodated ca. 6 mm/yr of slip over the last ca. 33-6 ka. Additionally, we speculate that slip is temporally partitioned between the two fault strands, implying that this part of the fault system is more complex than previously believed.
ContributorsBohon, Wendy (Author) / Arrowsmith, Ramon (Thesis advisor) / Hodges, Kip V (Thesis advisor) / Whipple, Kelin X (Committee member) / Heimsath, Arjun (Committee member) / Reynolds, Steven (Committee member) / Arizona State University (Publisher)
Created2014
Description
The action/adventure game Grad School: HGH is the final, extended version of a BME Prototyping class project in which the goal was to produce a zombie-themed game that teaches biomedical engineering concepts. The gameplay provides fast paced, exciting, and mildly addicting rooms that the player must battle and survive through, followed by an engineering puzzle that must be solved in order to advance to the next room. The objective of this project was to introduce the core concepts of BME to prospective students, rather than attempt to teach an entire BME curriculum. Based on user testing at various phases in the project, we concluded that the gameplay was engaging enough to keep most users' interest through the educational puzzles, and the potential for expanding this project to reach an even greater audience is vast.
ContributorsNitescu, George (Co-author) / Medawar, Alexandre (Co-author) / Spano, Mark (Thesis director) / LaBelle, Jeffrey (Committee member) / Guiang, Kristoffer (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
Description
The morphology of mountainous areas is strongly influenced by stream bed incision rates, but most studies of landscape evolution consider erosion at basin scales or larger. The research here attempts to understand the smaller-scale mechanics of erosion on exposed bedrock channels in the conceptual framework of an established saltation-abrasion model by Sklar and Dietrich [2004]. The recirculating flume used in this experiment allows independent control of bed slope, water discharge rate, sediment flux, and sediment grain size – all factors often bundled together in simple models of river incision and typically cross-correlated in natural settings. This study investigates the mechanics of erosion on exposed bedrock channels caused by abrasion of transported particles. Of particular interest are saltating particles, as well as sediment near the threshold between saltation and suspension - sediment vigorously transported but with significant interaction with the bed. The size of these erosive tools are varied over an order of magnitude in mean grain diameter, including a sand of D¬50 = 0.56 mm, and three gravel sizes of 3.39, 4.63, and 5.88 mm. Special consideration was taken to prevent any flow conditions that created a persistent alluvial cover. The erodible concrete substrate is fully exposed at all times during experiments reported here. Rates of erosion into the concrete substrate (a bedrock proxy) were measured by comparing topographic data before and after each experimental run, made possible by a precision laser mounted on a high speed computer-controlled cart. The experimental flume was able to produce flow discharge as high as 75 liters per second, sediment fluxes (of many varieties) up to 215 grams per second, and bed slopes up to 10%. I find a general positive correlation is found between erosion rate and bed slope, shear stress, grain size, and sediment flux.
ContributorsAdams, Mark (Author) / Whipple, Kelin (Thesis advisor) / Heimsath, Arjun (Committee member) / Schmeeckle, Mark (Committee member) / Arizona State University (Publisher)
Created2016
Description
For this dissertation, three separate papers explore the study areas of the western Grand Canyon, the Grand Staircase (as related to Grand Canyon) and Desolation Canyon on the Green River in Utah.
In western Grand Canyon, I use comparative geomorphology between the Grand Canyon and the Grand Wash Cliffs (GWC). We propose the onset of erosion of the GWC is caused by slip on the Grand Wash Fault that formed between 18 and 12 million years ago. Hillslope angle and channel steepness are higher in Grand Canyon than along the Grand Wash Cliffs despite similar rock types, climate and base level fall magnitude. These experimental controls allow inference that the Grand Canyon is younger and eroding at a faster rate than the Grand Wash Cliffs.
The Grand Staircase is the headwaters of some of the streams that flow into Grand Canyon. A space-for-time substitution of erosion rates, supported by landscape simulations, implies that the Grand Canyon is the result of an increase in base level fall rate, with the older, slower base level fall rate preserved in the Grand Staircase. Our data and analyses also support a younger, ~6-million-year estimate of the age of Grand Canyon that is likely related to the integration of the Colorado River from the Colorado Plateau to the Basin and Range. Complicated cliff-band erosion and its effect on cosmogenic erosion rates are also explored, guiding interpretation of isotopic data in landscapes with stratigraphic variation in quartz and rock strength.
Several hypotheses for the erosion of Desolation Canyon are tested and refuted, leaving one plausible conclusion. I infer that the Uinta Basin north of Desolation Canyon is eroding slowly and that its form represents a slow, stable base level fall rate. Downstream of Desolation Canyon, the Colorado River is inferred to have established itself in the exhumed region of Canyonlands and to have incised to near modern depths prior to the integration of the Green River and the production of relief in Desolation Canyon. Analysis of incision and erosion rates in the region suggests integration is relatively recent.
In western Grand Canyon, I use comparative geomorphology between the Grand Canyon and the Grand Wash Cliffs (GWC). We propose the onset of erosion of the GWC is caused by slip on the Grand Wash Fault that formed between 18 and 12 million years ago. Hillslope angle and channel steepness are higher in Grand Canyon than along the Grand Wash Cliffs despite similar rock types, climate and base level fall magnitude. These experimental controls allow inference that the Grand Canyon is younger and eroding at a faster rate than the Grand Wash Cliffs.
The Grand Staircase is the headwaters of some of the streams that flow into Grand Canyon. A space-for-time substitution of erosion rates, supported by landscape simulations, implies that the Grand Canyon is the result of an increase in base level fall rate, with the older, slower base level fall rate preserved in the Grand Staircase. Our data and analyses also support a younger, ~6-million-year estimate of the age of Grand Canyon that is likely related to the integration of the Colorado River from the Colorado Plateau to the Basin and Range. Complicated cliff-band erosion and its effect on cosmogenic erosion rates are also explored, guiding interpretation of isotopic data in landscapes with stratigraphic variation in quartz and rock strength.
Several hypotheses for the erosion of Desolation Canyon are tested and refuted, leaving one plausible conclusion. I infer that the Uinta Basin north of Desolation Canyon is eroding slowly and that its form represents a slow, stable base level fall rate. Downstream of Desolation Canyon, the Colorado River is inferred to have established itself in the exhumed region of Canyonlands and to have incised to near modern depths prior to the integration of the Green River and the production of relief in Desolation Canyon. Analysis of incision and erosion rates in the region suggests integration is relatively recent.
ContributorsDarling, Andrew Lee (Author) / Whipple, Kelin (Thesis advisor) / Semken, Steven (Committee member) / Arrowsmith, Ramon (Committee member) / DeVecchio, Duane (Committee member) / Heimsath, Arjun (Committee member) / Arizona State University (Publisher)
Created2016
Description
There is a need to understand spatio-temporal variation of slip in active fault zones, both for the advancement of physics-based earthquake simulation and for improved probabilistic seismic hazard assessments. One challenge in the study of seismic hazards is producing a viable earthquake rupture forecast—a model that specifies the expected frequency and magnitude of events for a fault system. Time-independent earthquake forecasts can produce a mismatch among observed earthquake recurrence intervals, slip-per-event estimates, and implied slip rates. In this thesis, I developed an approach to refine several key geologic inputs to rupture forecasts by focusing on the San Andreas Fault in the Carrizo Plain, California. I use topographic forms, sub-surface excavations, and high-precision geochronology to understand the generation and preservation of slip markers at several spatial and temporal scales—from offset in a single earthquake to offset accumulated over thousands of years. This work results in a comparison of slip rate estimates in the Carrizo Plain for the last ~15 kyr that reduces ambiguity and enriches rupture forecast parameters. I analyzed a catalog of slip measurements and surveyed earth scientists with varying amounts of experience to validate high-resolution topography as a supplement to field-based active fault studies. The investigation revealed that (for both field and remote studies) epistemic uncertainties associated with measuring offset landforms can present greater limitations than the aleatoric limitations of the measurement process itself. I pursued the age and origin of small-scale fault-offset fluvial features at Van Matre Ranch, where topographic depressions were previously interpreted as single-event tectonic offsets. I provide new estimates of slip in the most recent earthquake, refine the centennial-scale fault slip rate, and formulate a new understanding of the formation of small-scale fault-offset fluvial channels from small catchments (<7,000 m2). At Phelan Creeks, I confirm the constancy of strain release for the ~15,000 years in the Carrizo Plain by reconstructing a multistage offset landform evolutionary history. I update and explicate a simplified model to interpret the geomorphic response of stream channels to strike-slip faulting. Lastly, I re-excavate and re-interpret paleoseismic catalogs along an intra-continental strike-slip fault (Altyn Tagh, China) to assess consistency of earthquake recurrence.
ContributorsSalisbury, J. Barrett (Author) / Arrowsmith, Ramon (Thesis advisor) / Shirzaei, Manoochehr (Committee member) / DeVecchio, Duane (Committee member) / Whipple, Kelin (Committee member) / Heimsath, Arjun (Committee member) / Arizona State University (Publisher)
Created2016
Description
Mountain landscapes reflect competition between tectonic processes acting to build topography and erosive processes acting to wear it down. In temperate mountain landscapes, bedrock rivers are the primary erosional agent, setting both the pace of landscape evolution and form of the surrounding topography. Theory predicts that river steepness is sensitive to climatic, tectonic, and lithologic factors, which dictate the rates and mechanics of erosional processes. Thus, encoded into topography is an archive of information about forces driving landscape evolution. Decoding this archive, however, is fraught and climate presents a particularly challenging conundrum: despite decades of research describing theoretically how climate should affect topography, unambiguous natural examples from tectonically active landscapes where variations in climate demonstrably influence topography are elusive. In this dissertation, I first present a theoretical framework describing how the spatially varied nature of orographic rainfall patterns, which are ubiquitous features of mountain climates, complicate expectations about how climate should influence river steepness and erosion. I then apply some of these ideas to the northern-central Andes. By analyzing river profiles spanning more than 1500 km across Peru and Bolivia, I show that the regional orographic rainfall pattern this landscape experiences systematically influences fluvial erosional efficiency and thus topography. I also show how common simplifying assumptions built into conventional topographic analysis techniques may introduce biases that undermine detection of climatic signatures in landscapes where climate, tectonics, and lithology all covary – a common condition in mountain landscapes where these techniques are often used. I continue by coupling this analysis with published erosion rates and a new dataset of 25 cosmogenic 10Be catchment average erosion rates. Once the influence of climate is accounted for, functional relationships emerge among channel steepness, erosion rate, and lithology. I then use these functional relationships to produce a calibrated erosion rate map that spans over 300 km of the southern Peruvian Andes. These results demonstrate that accounting for the effects of climate significantly enhances the ability to decode channel steepness patterns. Along with this comes the potential to better understand rates and patterns of tectonic processes, and identify seismic hazards associated with tectonic activity using topography.
ContributorsLeonard, Joel Scott (Author) / Whipple, Kelin (Thesis advisor) / Arrowsmith, Ramon (Committee member) / Christensen, Philip (Committee member) / Forte, Adam (Committee member) / Heimsath, Arjun (Committee member) / Hodges, Kip (Committee member) / Arizona State University (Publisher)
Created2022
Description
The tectonism, volcanism, and sedimentation along the East African Rift System (EARS) produced a series of rift basins with a rich paleoanthropological record, including a Late Miocene–present record of hominin evolution. To better understand the relationship between Earth system history and human evolution within the EARS, the Hominin Sites and Paleolakes Drilling Project (HSPDP) collected paleolake sediments near key paleoanthropological sites in Ethiopia and Kenya, compiling a multi-proxy, high-resolution geological and environmental record. As part of the HSPDP, I studied the detrital mineral record of the basins and evaluated tectonic and climatic controls on East African landscapes during the Plio-Pleistocene using samples from three of the drill sites, Chew Bahir: (CHB, ~620–present; Ethiopia), Northern Awash (NA, ~3.3–2.9 Ma; Ethiopia,), and West Turkana (WTK, ~1.9–1.4 Ma; Kenya). I employed laser ablation U/Pb and (U-Th)/He double dating (LADD) of detrital zircons, which yields paired U/Pb and (U-Th)/He dates, and (U-Th)/He dating of detrital apatites to evaluate sediment provenance and the cooling history of the source rocks. In addition, I used in situ 10Be cosmogenic radionuclide analyses to determine paleoerosion rates. Two chapters of this dissertation focus on results from the NA and WTK drill sites. Source units for the NA and WTK drill sites are largely Cenozoic volcanic rocks, and the detrital zircon record yields an extensive record of the timing of various phases of volcanism within the EARS. Exceptionally young zircon (U-Th)/He dates reflect partial resetting associated with late mafic volcanism and/or hydrothermal activity. Erosion rates are consistent and relatively low across the Plio-Pleistocene, despite significant tectonic and geomorphic shifts in the landscape. Two other chapters of this dissertation cover results from the CHB drill site. The Chew Bahir basin has significant exposures of Neoproterozoic and Early Paleozoic crystalline basement units, and the detrital zircon record yields one singular phase of volcanism in the EARS. The CHB erosion rates show an overall decreasing trend over time, consistent with an aridifying climate, and increased environmental variability after ~200 ka.
ContributorsZawacki, Emily Elizabeth (Author) / Arrowsmith, J Ramon (Thesis advisor) / Campisano, Christopher (Thesis advisor) / Heimsath, Arjun (Committee member) / Hodges, Kip (Committee member) / Whipple, Kelin (Committee member) / Arizona State University (Publisher)
Created2021
Description
The mountains of western North America are spectacular and diverse, from sheer walls of crumbling black limestone in the Canadian Rockies, to smooth glacially polished granite in the Wind River Range, to gargantuan ice-clad volcanoes in the Cascades. These great bastions of rock, snow, and ice, still very much wild and untamed, provide an incredible arena for adventure, exploration, and challenge. Over the past three years, I have devoted thousands of hours to exploring these vast wild places, climbing high peaks, steep cliffs, and frozen waterfalls. In doing so, I studied the rich geologic history of the mountains. This thesis project is a compilation of stories and images from those adventures, along with the stories of the mountains themselves: how the rocks were formed, thrust skyward, and sculpted over the ages into their present, glorious form. The photographic and detailed narrative of the geology and adventures is on a new website called Cloud Piercers, which currently features three geologically diverse mountain massifs: (1) Mount Rainier, an active volcano in the Cascade Range of Washington; (2) Mount Robson, the highest peak in the Canadian Rockies, within a terrain of folded Paleozoic sedimentary rocks; and (3) the Wind River Range of Wyoming, composed mostly of Archean metamorphic and granitic rocks. This website will be expanded in the future as the geologic studies and adventures continue.
ContributorsSteadman, Dane Kyle (Author) / Reynolds, Stephen (Thesis director) / Johnson, Julia (Committee member) / Heimsath, Arjun (Committee member) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Faults found in the arid to semi-arid Basin and Range Physiographic province of the southwestern US are given broad age definitions in terms of which features appear to be the oldest. Particularly in the northwestern corner of Arizona, detailed geomorphic studies on the tectonic history and timing of faulting are not widespread. At the base of the Virgin Mountains in northwestern Arizona is a fault scarp along the Piedmont Fault line. This normal fault crosses a series of alluvial fans that are filled with sediments of ambiguous ages. Previous studies that were done in this region find a broad, Miocene age for the exhumation and uplift of these surfaces, with some indications of Laramide faulting history. However, specific fault characteristics and a time constraint of the tectonic history of the Piedmont Fault scarp has yet to be established. Here, we aim to determine the age, fault-slip rate, seismic history, and potential hazard of the fault scarp near Scenic and Littlefield, Arizona through structure from motion (SfM) modeling, which is a form of photogrammetry using a drone. In addition, we distinguish the climatic and tectonic influences on the geomorphology observed along the scarp through analysis along the fault line. With data collected from a ~500 m section of the fault, we present results from a digital elevation model (DEM) and orthophotos derived through the SfM modelling. Based on field observations and morphologic dating, we determine that the Piedmont Fault experiences an approximately continuous fault-slip and an earthquake recurrence interval in the range of 7,000 years. The approximate age of the scarp is 16.0 ka ± 5 kyr. Therefore, we conclude that the earthquake hazard posed to nearby cities is minimal but not nonexistent. Future work includes further analysis of fault profiles due to uncertainty in the present one and Terrestrial Cosmogenic Nuclide (TCN) dating of samples taken from the tops of boulders in a residual debris flow sitting on faulted and unfaulted alluvia. Determining the ages for these boulder surfaces can hopefully further inform our knowledge of the tectonic activity present in the North Virgin Mountains.
ContributorsApel, Emily Virginia (Author) / Heimsath, Arjun (Thesis director) / Arrowsmith, Ramon (Committee member) / Whipple, Kelin (Committee member) / School of Molecular Sciences (Contributor) / School of International Letters and Cultures (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12